7 Jun
2002
7 Jun
'02
4:55 a.m.
I worked with a 6809 system back in the early 80s which
had an LED board to display the state of all of the system
signals. I don't recall the OP code, but there was one
which would continuously cycle the address, data, and
other signals until reset. It made the LEDs light up
like a christmas tree.
--tom
At 09:33 AM 6/7/02 -0700, you wrote:
From: "Ben
Franchuk" <bfranchuk(a)jetnet.ab.ca>
Loboyko Steve wrote:
Hi
Instructions that would continuously increment the address
are vary useful for debugging address decoding problems.
On an 8080, about the only useful sequence is to have
a pop and jmp, using 4 locations.
It may have been that the 6800 one was a debug instruction
that was designed in.
Dwight
I'm building a 6800 machine right now and I was
wondering about this "Halt and Catch on Fire"
instruction. Is this for real. This is a serious
question. Is there actually an instruction that will
overheat the chip?
Not on the 6800 but I believe some FORTH chips have that problem.
This instruction for the 6800 if remember right just continually
increments the address bus, ignoring any data read. Only a hard
RESET will reset the machine from this state. I think the opcode
is $00.